CN88101607A

CN88101607A - Concrete compound pipe and manufacture method thereof

Info

Publication number: CN88101607A
Application number: CN88101607.1A
Authority: CN
Inventors: 吉川信义; 浅野宽芝
Original assignee: Noritake Corp; Teikoku Hume Pipe Co Ltd
Current assignee: Noritake Corp; Teikoku Hume Pipe Co Ltd
Priority date: 1987-03-24
Filing date: 1988-03-23
Publication date: 1988-10-19
Also published as: DE3860231D1; US4976291A; EP0284317A1; KR880011514A; CN1015924B; JPH068676B2; AU1332688A; KR920002318B1; EP0284317B1; JPS63235783A; US5035850A; AU591388B2

Abstract

Concrete-type composite pipe has a cylindrical concrete layer and anti-corrosion layer formed on the inner surface of a drum mold; there is an intermediate resin/concrete layer between the concrete layer and the anti-corrosion layer, and its characteristics are between the concrete layer and the anti-corrosion layer between. The composite pipe is manufactured by the following method, the drum mold is rotated and the concrete is poured into it, and a concrete layer with uniform thickness is formed under the action of centrifugal force, and the mixture of hydrophilic resin and hardener is poured into the inner surface of the concrete layer before it solidifies. Form a resin layer on the top, spread fillers etc. on the inner surface of the resin layer, accelerate the rotation to make the fillers penetrate into the resin layer to form an anti-corrosion layer, and stop the rotation after the anti-corrosion layer is cured.

Description

Concrete type composite pipe and manufacturing method thereof

The present invention relates to a concrete type composite pipe having high rigidity and strength and resistance to corrosion by chemicals, and a method for manufacturing the same.

Conventional concrete type pipes are relatively rigid and inexpensive, but are difficult to resist corrosion by chemicals.

The artificial resin type pipe has good corrosion resistance and strength against chemicals. But such tubes are less rigid and costly.

Further, there has been also known a concrete type composite pipe in which a corrosion prevention layer is formed on the inner or outer surface of the pipe, the corrosion prevention layer being composed of a pitch-epoxy resin or a mixture of an epoxy resin and a filler, and a corrosion prevention layer is formed on both the inner and outer surfaces of a steam-treated concrete layer of a concrete type pipe having a large rigidity formed by a conventional inexpensive method. However, the corrosion protection layer is liable to peel off near the boundary of the concrete layer due to the difference in thermal expansion coefficient and contraction coefficient between the concrete layer and the corrosion protection layer, and thus the composite pipe is not ideal in terms of its strength and resistance to corrosion by chemicals.

The anticorrosive coating is generally formed by pouring resin and filler into a container and mixing them, and after the concrete layer is steamed, moving the container to pour the mixture on the inner surface of the concrete layer, so that the mixture spreads by centrifugal force, and complicated and troublesome operations are required for mixing the materials and transferring the resin. In addition, since the mixture lacks fluidity, a long time is required before forming a resin layer having a uniform thickness.

The invention aims to provide a novel concrete type composite pipe and a manufacturing method thereof.

According to one aspect of the present invention, a concrete type composite pipe comprises a cylindrical concrete layer, a corrosion prevention layer concentrically stacked on the cylindrical concrete layer, the corrosion prevention layer being composed of a mixture of a resin and a filler or the like, and a mixed intermediate layer composed of a resin and a concrete in an intermediate region between the concrete layer and the corrosion prevention layer, the mixed intermediate layer having a property between the concrete layer and the corrosion prevention layer.

According to another aspect of the present invention, a method of manufacturing a composite pipe of concrete type comprises the steps of: 1) rotating a drum mold around its own axis, 2) pouring concrete into the drum mold, the poured concrete forming a concrete layer of uniform thickness on the inner surface of the drum mold under the centrifugal force generated as the drum mold rotates, 3) accelerating the drum mold to increase the centrifugal force so that water is extruded out of the concrete layer to be accumulated on the inner surface of the concrete layer, 4) stopping the rotation of the drum mold to discharge the extruded water out of the concrete layer, 5) re-rotating the drum mold while pouring a mixture of a hydrophilic resin and a hardening agent into the mold so that they form a resin layer on the inner surface of the concrete layer before the concrete layer is solidified under the centrifugal force generated by the rotating drum mold, 6) continuing the rotation of the drum mold to spread a filler or the like on the inner surface of the resin layer, 7) accelerating the drum mold to increase the centrifugal force, so that the filler or the like penetrates into the resin layer to form an anticorrosive layer, and 8) stopping the rotation of the drum mold after the anticorrosive layer is cured.

FIG. 1A is a front view, in cross-section, of a concrete type composite pipe of the present invention;

FIG. 1B is a side view of the tube shown in FIG. 1A;

FIG. 2A is a front view showing an apparatus for manufacturing a pipe by the method for manufacturing the concrete type composite pipe shown in FIGS. 1A and 1B;

FIG. 2B is a cross-sectional view taken along line X-X in FIG. 2A;

fig. 3 is a cross-sectional side view of the apparatus shown in fig. 2A and 2B, illustrating a step of forming a resin layer of the concrete type composite pipe;

figure 4 is a cut-away side view of the same apparatus showing the step of spreading the filling material inside the tube.

An embodiment of the concrete type composite pipe of the present invention will be described below with reference to the accompanying drawings.

Fig. 1A and 1B show a composite pipe a of a concrete type having a layered structure, which comprises a concrete layer 1 and a corrosion prevention layer 2 formed on an inner surface of the concrete layer 1, the corrosion prevention layer 2 being composed of a mixture of a resin and a filler, where the "filler" generally means ground slag, dried sand or gravel, or a filler such as silica sand or calcium carbide, which may be used separately or blended together. At the boundary area between the concrete layer 1 and the corrosion protection layer 2, a mixed intermediate layer 4 is formed, the intermediate layer 4 consisting of coarse-grained filler 3, resin and concrete partially penetrating into the concrete layer 1.

The mixed intermediate layer 4 composed of resin and concrete has characteristics such as a thermal expansion coefficient and a contraction coefficient between both the concrete layer 1 and the anticorrosive layer 2. Therefore, even if the pipe is affected by a change in temperature or shrinkage is unavoidable when the concrete or the like is solidified, stress caused by the change in temperature and shrinkage caused between the concrete layer 1 and the anticorrosive layer 2 when they are solidified are reduced, so that peeling of the layers of the pipe is not caused.

Thus, the concrete layer 1 and the anticorrosive layer 2 are firmly and tightly joined together by the mixed intermediate layer 4 composed of resin and concrete into an integral structure, so that the concrete layer 1 itself maintains a great rigidity, and the anticorrosive layer 2 also has a great strength and a strong resistance to chemicals.

The outer layer in the above embodiments is composed of a concrete layer, however, the outer layer of the concrete type composite pipe may be made into an anticorrosive layer, or the anticorrosive layer may be formed on both the inner and outer surfaces of the concrete layer.

A method of manufacturing a concrete type composite pipe having a mixed intermediate layer composed of resin and concrete, in which the outer layer of the pipe is a concrete layer and the inner layer of the pipe is a corrosion prevention layer, according to an embodiment of the present invention, which is manufactured in the following sequence of steps, will now be described with reference to the accompanying drawings.

1) Step of forming the concrete layer 1:

as shown in fig. 2A and 2B, a side mold frame 5 is fixed to both ends of a drum mold 6, and the side mold frame is placed on a driving roller 7 and a driven roller 8. The driving force is transmitted to the driving roller 7 by a motor (not shown), and then drives the drum-shaped die 6, so that the centripetal acceleration of the inner circumference of the drum-shaped die usually reaches 3g-5g, and the maximum is 15 g.

In this case, a movable conveyor 9 is introduced through an opening 5a in one side formwork panel 5 in the longitudinal direction, and concrete is poured or poured into the drum mould 6 by the conveyor 9. The movable conveyor 9 then exits from the drum mould 6 through the opening 5a and stops at a predetermined position. In the other direction, in the drum mould 6, a concrete layer of uniform thickness is formed on its inner surface. After that, the output power of the motor is increased to increase the rotation speed of the drum mold 6 so that the centripetal acceleration of the inner surface of the drum mold 6 reaches 20g to 50g, preferably 30g to 40 g. Thus, water in the concrete layer is squeezed out, so that the concrete layer is tightly combined or physically hardened. The time required for this step depends on the final thickness of the pipe, the consistency of the concrete and the magnitude of the centrifugal force. Generally, it takes about 15 minutes to process a pipe having a diameter of 500 mm, and 40 to 60 minutes to process a pipe having a diameter of 3 m.

In this case, the radially inner part of the concrete layer 1 is combined with a larger part of cement and fine aggregate, so that this part of the area is relatively soft. Since the innermost part of the tube is water, after the time mentioned above, the drum mould is stopped in order to drain the water.

2) Step of forming the anticorrosive layer 2:

i) when the concrete layer is tightly combined or physically hardened by external force but not chemically hardened, it is known as new-cast concrete. The step of forming the corrosion protection layer 2 must be started before said fresh concrete is chemically hardened. Immediately after the drum mold stops rotating, an injection pipe 10 is inserted into the drum mold 6 in the longitudinal direction through the opening 5 a. Then, a valve (not shown) is opened, and a hydrophilic resin mixed with a hardening agent (e.g., two liquid type water-emulsified epoxy resins) is injected, and at the same time, the drum mold 6 is again actuated to make the centripetal acceleration of the inner surface of the drum mold 6 reach 5g to 20 g.

In this case, the resin having good fluidity is rapidly diffused over the concrete layer 1 due to the centrifugal force, so that the resin layer 11 having a uniform thickness can be formed in a short time.

As mentioned above, the resins must be hydrophilic because they are in contact with the not yet cured concrete layer 1.

The hydrophilic resin used in this example, in which a bisphenol A type Epoxy resin (Yuka Shell Epoxy Co., Ltd., each product of EPIKOTE 828) was emulsified with water in a ratio of 1 to 40 parts by weight of the resin. After the above treatment, Dez331 of Dow chemical Co., Ltd. or AER331 of Asahi Kasei Co., Ltd. was used again. In the above process, water preferably accounts for only a small proportion.

In another aspect, the hardener includes polyamidoamines, modified polyamidoamines, aliphatic polyamines, modified aliphatic polyamines, and the like. Mixing 30-70 parts by weight of any of the above hardeners with 100 parts by weight of a hydrophilic resin.

The spray tube 10 shown in FIG. 3 has an inner diameter of 2 to 3 cm, and the hydrophilic resin is discharged therefrom at a rate of 0.2 to 0.4 m/sec. In addition, a hardener tube 10' communicates with the injection tube 10 at a distance of 1.2 m from the nozzle opening, even if the weight part of the hardener in their mixture is 70. However, since the resin typically takes about seven minutes to cure, the tube 10 is not obstructed.

After the resin layer 11 is formed, the injection tube 10 is rapidly drawn out of the drum mold 6 through the opening 5a and placed at a predetermined position of the drum mold.

Ii) placing an injection hopper into the drum mould 6 immediately after the injection pipe 10 has been withdrawn from the drum mould 6. As shown in fig. 4, the longitudinal length of the hopper 12 is substantially the same as that of the drum mold 6, and a filler or the like is filled therein. The filler or the like is spread over the inner surface of the resin layer 11 through the bottom-opening door 12 a.

The hopper 12 is then withdrawn from the drum mould 6 through the opening 5a and parked in another predetermined position. Meanwhile, the output power of the motor is improved, so that the centripetal acceleration of the die can reach 10g-15g optimally, and 30g-40g maximally.

Since the hopper 12 has substantially the same length as the drum mold 6 in the longitudinal direction, the filler 13 is uniformly spread over the resin layer 11 in a short time. After the drum mold 6 is rotated for an appropriate time in this case, it is stopped after the resin is cured.

The ratio of resin to filler can vary widely according to this manufacturing process.

Iii) in the above step ii), the filler 13 floats on the resin layer 11 at the start of spreading. The coarse particles in the filler 13 then penetrate into the not yet solidified concrete layer 1 under the influence of centrifugal force. Thus, a mixed intermediate layer 4 composed of resin and concrete is formed, the intermediate layer 4 having a characteristic of being interposed between the concrete layer 1 and the anticorrosive layer 2, as shown in fig. 1A and 1B.

Since the relatively fine particles in the filler 13 are distributed near the inner surface of the anticorrosive layer 2, a smooth surface having a small roughness coefficient can be obtained.

If it is desired to manufacture the concrete composite pipe a having high corrosion resistance to chemicals and high strength, the thickness of the anticorrosive coating 2 must be increased to meet the need.

The composite pipe in which the inner layer is the corrosion prevention layer has been described above. If the outer layer of the composite pipe is also made into an anticorrosive layer, the outer anticorrosive layer is made by a centrifugal method, and when the anticorrosive layer is not solidified under the centrifugal action, concrete is poured on the inner surface of the anticorrosive layer. The inner surface and the outer surface of the concrete layer can also be made into an anti-corrosion layer.

It was found through experiments that the concrete type composite pipe manufactured according to the above method did not show peeling even when the outer surface of the composite pipe of the present invention was heated to 90 c and the inner surface was heated to 50 c.

1. The concrete type composite pipe of the invention has the following advantages and effects:

i) greater rigidity and strength, and good corrosion resistance.

Ii) the mixed middle layer has reliable protection effect on the concrete layer and the anticorrosive layer, so that the concrete layer and the anticorrosive layer can not be peeled off.

2. The method for manufacturing the concrete type composite pipe of the present invention has the following advantages and effects:

i) continuously spreading the resin and the filler on the concrete layer which is not solidified, and centrifugally forming the anticorrosive layer, whereby the mixed intermediate layer composed of the resin and the concrete is formed to have a characteristic of being interposed between the concrete layer and the anticorrosive layer.

Ii) the poured resins have good fluidity, and they are rapidly dispersed by centrifugal force, thereby forming a resin layer having a uniform thickness in a short time.

Iii) the filler to be introduced after the resin is sprinkled from a hopper having a length approximately equal to the length of the concrete layer, so that the filler is also distributed uniformly over the resin layer in a short time.

Iv) the resin and the filler are separately placed in the mold with a structurally simple apparatus because of high economy. In addition, after the device is used, the cleaning device is easy, and labor is saved.

Claims

1. A concrete type composite pipe comprising:

a cylindrical concrete layer;

a corrosion prevention layer concentrically stacked on the cylindrical concrete layer, the corrosion prevention layer being formed of a mixture of a resin and a filler or the like;

a mixed intermediate layer composed of resin and concrete, the intermediate layer being located in a boundary region between the cylindrical concrete layer and the anticorrosive layer, the mixed intermediate layer having a characteristic of being interposed between the concrete layer and the anticorrosive layer.

2. The concrete type composite pipe as claimed in claim 1, wherein the corrosion prevention layer is located radially inside the cylindrical concrete layer.

3. A method for manufacturing a composite pipe of the concrete type comprising the steps of:

1.) rotating a drum mold about its own axis;

2) pouring concrete into the drum-shaped mould, wherein a layer of concrete layer with uniform thickness is formed on the inner surface of the drum-shaped mould under the action of centrifugal force generated by the rotation of the poured concrete along with the drum-shaped mould;

3) accelerating the drum mould to increase centrifugal force, whereby water is forced out of the concrete layer to collect on the inner surface of the concrete layer;

4) stopping the rotation of the drum-shaped die and discharging the extruded water out of the concrete layer;

5) rotating the drum mold again while pouring a mixture of a hydrophilic resin and a hardening agent into the mold so that they form a resin layer on the inner surface of the concrete layer before the concrete layer is solidified under the centrifugal force generated by the rotating drum mold;

6) continuing to rotate the drum mold to dispense a filler or the like on the inner surface of the resin layer;

7) accelerating the drum mold to increase a centrifugal force, thereby allowing the filler or the like to penetrate into the resin layer to form an anticorrosive layer;

8) the rotation of the drum mould is stopped after the corrosion protection layer has cured.

4. The method of manufacturing a concrete type composite pipe according to claim 3, wherein the centrifugal acceleration in step 2) is 15g or less.

5. The method for manufacturing a concrete type composite pipe according to claim 3, wherein the centrifugal acceleration in the step 3) is 20g to 50 g.

6. The method for manufacturing a concrete type composite pipe according to claim 3, wherein the centrifugal acceleration in the step 5) is 5g to 20 g.

7. The method for manufacturing a concrete type composite pipe according to claim 3, wherein the centrifugal acceleration in the step 7) is 10g to 40 g.